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Feature-Matching in AAC Assessment: Access Features

Updated: Jun 6, 2023

Feature-matching is a systematic process in which an AAC user’s strengths and needs are matched to available tools and strategies (Shane & Costello, 1994). It's important to remember that with feature-matching we are considering both current and future needs (Gosnell., 2011).

During the feature-matching process, access methods are important to trial and assess for a user, particularly for those with fine and/or gross motor deficits as well as for those with hearing and/or vision impairments.

  • For an AAC user to have the success using their AAC system for communication, they must be able to consistently and accurately access their device.

  • Because of technological advances, there are more and more access methods available for individuals with complex access needs meaning there are many different features to consider when assessing and making recommendations related to access features.

Forbes AAC offers many different access methods for our AAC users.

  • Through our WinSlate™ Series, users can access their device via head mouse, switch scanning, direct selection with a body part or a stylus, or eye tracking.

  • With our ProSlate™ Series, users can access their device via direct selection using a body part, such as a finger, or by using a stylus as well as through switch scanning.

  • For both devices, the SnapLock™ Keyguard is available! The SnapLock keyguards give users more control by allowing them to rest their palm on the face of the device without making inadvertent presses on the touch panel.

How do we make decisions related to the many different access features available? We can break it down by first determining the user's access method type and then deciding on the relevant access method features for each individual user.

  • Access to a speech-generating device (SGD) can be categorized by direct access and indirect access. Direct access includes pointing, touching/pressing, eye gaze, mouse control, and head pointing. Indirect access includes switch canning.

  • According to ASHA (n.d.), direct selection can be done through nonelectronic or electronic means. Nonelectronic would be through the use of direct physical touch while electronic would be through the use of a generated movement or signal (e.g., eye gaze, head mouse).

For each access method, we must consider some of the following features:

Direct Physical Touch:

  • With this method, we must consider the user's need for a keyguard and/or the use of a stylus. With our SnapLock™ Keyguards, they can be customized in their layout and button shape (e.g., large or small, circle or square). Keyguards are beneficial for users who have difficulty with finger isolation or need additional support.

  • It's also important to make modifications of any touch screen settings that may benefit a user. There are many settings options depending on the AAC device, language system, and/or AAC app including release time, delay time, or dwell settings.

Mouse Options:

  • The use of electronic direct selection can also be done using mouse options. This is a great access method option for a user who cannot access their device using a standard mouse.

  • There are many types of mouse options including a head mouse or a joystick and within these choices there are features to consider such as selection method (e.g., when releasing, dwell), type of feedback (e.g., auditory, visual), and type of indicator.

Eye Tracking:

  • With this access method, there are setting adjustments that should be addressed during the assessment process to ensure the user is able to accurately access the AAC system.

  • Calibration settings such as calibration point or the size of calibration points can provide a user with a much better calibration, thus more accurate and efficient access to their device. For example, with pediatrics, using a our animation calibration points like Batman or a dog may be more engaging for the user allowing for a better calibration.

  • Other eye gaze features to consider include dwell selection. With our WinSlate device, you can make many modifications to the dwell selection feature including the dwell indicator (e.g., full circle, shrinking dot) and dwell time. Editing these features can be crucial to meet a user's needs in terms of the timing and access to their button target.

Switch Scanning:

  • For AAC users who are unable to use direct selection, the use of scanning methods are recommended. There are so many different ways to adjust and adapt switch scanning to meet the needs of an AAC user!

  • Switch options such as a proximity switch, finger isolation switch, or a button switch are determined based on a users fine/gross motor abilities and with the use of these switch options, a user can access their device with one or two switches.

  • There are many other features to consider including the switch pattern (e.g., linear, row-column, snake), the scan method (e.g., step-scanning, auto scanning), and the type of feedback a user receives (e.g., auditory, visual). All of these features can be adapted to best meet the user's needs.

Feature-matching is a complex process, but a necessary component for an AAC assessment. Continue to follow our blog posts the next few weeks to learn more!


  • American Speech-Language-Hearing Association (n.d.). Augmentative and Alternative Communication (Practice Portal).

  • Beukelman, D. R., & Light, J. C. (2020). Augmentative & alternative communication: Supporting children and adults with complex communication needs (5th ed.). Brookes.

  • Gosnell, J., Costello, J., & Shane, H. (2011). Using a clinical approach to answer “what communication apps should we use?” SIG 12 Perspectives on Augmentative and Alternative Communication, 20(3), 87–96.

  • Locast, M. & Marx, A. (2016). AAC Feature Matching Overview [Presented at The American Academy for Cerebral Palsy and Developmental Medicine AACPDM) Annual Meeting]. Accessed from: (June 8th, 2022).

  • Shane, H., & Costello, J. (1994, November). Augmentative communication assessment and the feature matching process. Mini-seminar presented at the annual convention of the American Speech-Language-Hearing Association. New Orleans, LA.

Katie Threlkeld, M.S., CCC-SLP is a licensed, ASHA-certified speech-language pathologist and the Educational Program Developer at Forbes AAC. She has over eight years of experience in AT and AAC assessment and treatment with both the pediatric and adult populations. Katie has presented at the state and national level on AAC topics and she has University teaching experience at the undergraduate and graduate level.

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